Have 2000 rodeo and now air conditioner condensation backing up into passenger floorboard! AC still works good air is nice and cold. A little condensation drains to outside but most comes inside. What can cause this and how do i fix???

They usually get clogged by leaves getting into the fan and blown into the evaporator case, or sometimes by slime mold if it stays wet enough for long periods of time.

Usually you can poke something in the drain tube on the firewall side, or blast some compressed air into it to loosen up the gunk thats clogging it.

thanks for the advice, but no luck still water coming inside! Will i have to take it all apart under the dash to clean this out now?